1. Field of the Invention
This invention relates generally to implantable devices for interventional therapeutic treatment of defects in the vasculature, and more particularly concerns a detachable device having multiple strut members with collapsed and expanded configurations to be used in combination with a catheter for the occlusion and reinforcement of aneurysms.
2. Description of Related Art
Recently developed interventional procedures have been used to treat defects in the vasculature which are not easily reached by surgical procedures. More particularly, such interventional procedures have been developed to treat defects that are located in small and remote vessels such as those within the brain. During such interventional procedures, vasoocclusive devices are typically placed within the vasculature of the human body by use of a catheter, either to block the flow of blood through a vessel making up that portion of the vasculature through the formation of an embolus, or to form such an embolus within an aneurysm stemming from the vessel. Vasoocclusive devices used for these procedures can have a variety of configurations, and are generally formed of one or more elements that are larger in the deployed configuration than when they are within the delivery catheter prior to placement. One anatomically shaped vasoocclusive device that forms itself into a shape of an anatomical cavity such as an aneurysm is made of a preformed strand of flexible material such as a nickel-titanium alloy. One or more of such vasoocclusive members can be wound to form a generally spherical or oval shape in a relaxed, expanded state, and can be readily deformed to fit within a small diameter catheter from which they can be deployed at a treatment site.
Aneurysms have been treated with external surgically placed clips, or using vascular catheters, by detachable vasoocclusive balloons or an embolus generating vasoocclusive device such as one or more vasoocclusive coils. The delivery of such vasoocclusive devices can be accomplished by a variety of means, including via a catheter in which the device is pushed through an opening at the distal end of the catheter by a pusher to deploy the device. By using highly flexible materials for the vasoocclusive devices, the vasoocclusive devices can be produced in such a way that they will readily pass through the lumen of a catheter in a linear shape and take on a complex shape as originally formed after being deployed into the area of interest, such as an aneurysm.
One vasoocclusive device used to treat aneurysms is a tightly wound coil that is pushed into the aneurysm through the neck of the aneurysm so that the coil forms a complex shape with the aneurysm. When an embolus generating vasoocclusive device such as a vasoocclusive coil is used to treat an aneurysm, the success of the treatment depends upon whether the embolus generating vasoocclusive device can migrate out of the aneurysm through the neck of the aneurysm, which in turn is somewhat dependent upon whether the ratio of the diameter of the dome portion of the aneurysm to the diameter of the neck of the aneurysm is less than approximately 2:1. If the dome to neck ratio is larger than approximately 2:1, the possibility that the embolus generating vasoocclusive device will migrate out of the aneurysm into the parent vessel becomes greater, posing a risk to the success of the procedure.
It would, therefore, be desirable to provide a vasoocclusive device that can be used with or without a stent, coil or the like, that can be delivered to an aneurysm or other body vessel in a primary collapsed configuration, where the vasoocclusive device can be deployed and released to assume a secondary, expanded configuration which partially occludes the neck of the aneurysm and which also allows deployment of an additional embolus generating vasoocclusive device such as an embolic coil within the aneurysm, and blocks migration of the embolus generating vasoocclusive device from the aneurysm to the vessel. It would also be desirable to provide a device which offers the advantages of a shape memory alloy such as a nickel-titanium alloy, and that incorporates radiopaque material in a stable configuration that is not subject to fracture during use of the device, so that the device can be visualized under fluoroscopy. The present invention meets these and other needs.